At present we know many kinds of helmets made specially to be used in sports.
They are basically composed of an envelope that covers the head of the person to be protected. This envelope was traditionally made of metallic material, so as to withstand blows. More recently, it has been made of plastic materials, generally with glass fiber for lighter weight, greater elasticity and cushioning with acceptable mechanical resistance and hardness.
These helmets have other advantageous characteristics, such as an elastic inner layer to cushion the effects of blows and to achieve a certain reduction of outside noise, ventilation holes, etc.
Nonetheless, despite the advantages offered by modern helmets used especially in sports, all have the disadvantage of the space they occupy, which is often bothersome.